Fibrous structures and methods of making the same



Nov. 28, 1961 F. H. SEXSMITH FIBROUS STRUCTURES AND METHODS OF MAKING THE SAME Filed March 27, 1959 ATTORNEY Unite rates opee Manufacturing Company, a corporation of Massachusetts Filed Mar. 27, 1959, $61. No. 802,373 7 Claims. Cl. 154-46) The present invention relates to improved fibrous or filamentous structures and to methods of bonding the same and more particularly is concerned with improved bonding methods wherein synthetic or man-made polymen'c fibrous or filamentous materials of a high molecular weight are bonded and simultaneously strengthened without loss of their fibrous character.

Fibrous structures and similar materials, of which nonwoven textile fabrics are a notable example, are soft and flexible but normally are weak and unable to resist laundering and washing, or tearing, abrading, elongating, or other disrupting forces. One method of improving the properties of such fibrous materials has involved the use of synthetic, potentially adhesive or fusible fibers therein whereby treatment with agents capable of fusing the fibers has autogenically bonded the fibrous material into an integral and relatively strong structure. Such autogenic fusing agents have included heat and/or pressure or solvents for the potentially fusible fibers or various combinations thereof. The use of these fusing agents and the attendant activating treatment has, however, customarily been relatively light in order that the fibrous character of the starting material be maintained. Such light treatment has resulted in moderate increases in launderability, strength and resistance to abrasion of the fibrous materials, whereby their use has been enhanced.

Unfortunately, the increase in launderability, strength and improved resistance to abrasion has not been as great as desired for some uses and consequently the treatment with the fusing agent has been increased in severity at times. Such has led to the desired strength and abrasion resistance but only at the loss of the fibrous character of the starting material which was converted to a stifi, boardy material lacking in softness, flexibility, hand and drape. As a result, the increase in strength and abrasion resistance was limited by the necessity of maintaining the basic fibrous character of the starting material.

It is therefore a principal object of the present invention to provide an improved method of bonding fibrous materials wherein desired launderability, increased strength and improved abrasion resistance are realized without 10% of the fibrous character of the starting material.

It has been found that, if (1) there is included in the starting fibrous material a sufiicient amount of potentially adhesive or fusible synthetic fibers, and (2) the fusing agent comprises a solvent which is also capable of containing therein a suificient amount of a dissolved organic, synthetic or man-made polymeric, high molecular weight material, preferably of the same organic chemical nature as the synthetic fusible fibers, the resulting treated fibrous structure is not only strengthened and its abrasion resistance and launderability improved by the autogenic bonding due to the solvent treatment but is additionally improved by the deposition of the dissolved polymeric material, notably at the intersections and other contacting portions of the fibers in the fibrous structure, without any loss in the fibrous character of the starting materials.

More specifically, it has been found that aqueous solutions of chloral or chloral hydrate are capable of fulfilling all the necessary bonding and dissolving requirements but at the same time they are capable of avoiding the 3,010,858 Patented Nov. 28, 1961 disadvantages noted hereinabove, particularly that of the loss of the fibrous character of the starting material. Additionally, chloral has almost unlimited solubility in water, thereby making aqueous solutions thereof avail able in substantially any desired concentration. And, furthermore, the vapor pressure of chloral is practically the same as water whereby standard heating and drying operations including air drying can substantially simultaneously remove both the chloral residues and the water from the treated material in one operation.

Chloral, which term shall hereinafter include aqueous solutions thereof as chloral hydrate, is used in concentrations such that the chloral ranges from about 45% by volume up to slightly below 100%, say, up to about 99% Within the more commercial aspects of the present invention, however, concentrations of from about 55% by volume to about 95% by volume are preferred, with optimum results being obtained in the range of from about to about Any fiber or filament which is capable of being ren dered tacky or fusible, or of being dissolved by chloral, may be employed within the application of the present invention. Polyesters, such as made of polyethylene terephthalate and sold under the registered trademarks Dacron, Kodel, Teron, and Terylene, are well suited for the purposes of the present invention. Other suitable fibers and filaments include: the polyamides, notably diamine-diacid nylon 66 and polycaprol-actam nylon 6 such as Caprolan; the acrylics such as Orlon and Acrilan; the vinyls such as Dynel and Vinyon; the cellulose esters such as Arnel and Tricel (cellulose triacetate); etc.

it is not essential that the starting fibrous material consist of only one type of these synthetic fibers. Blends of 2 or more of these fibers in substantially any proportion by weight may be used. Fibers which are not affected by chloral may also be included in certain proportions in the base web or fibrous substrate, provided the percentage is not too high as to prevent the development of sufiicient fusibility or tackiness. Depending upon the requirements of the particular bonded product, percentages of nonaffected fibers ranging from a few percent to as high as about percent by weight, and preferably from about 10 percent to about 60 percent by weight, may. be used. Examples of such fibers which are not affected by chloral are natural fibers, notably cotton, and synthetic fibers, notably regenerated cellulose, such as viscose rayon or cuprammonium rayon; polypropylene; etc.

In the event that greater than 95 by Weight of nonaifected fibers is included, the bonding effect is decreased to a point until, with a starting material containing of non-affected fibers, there is substantially no autogenic bonding. However, the coating of the fibers of the starting material with chloral-polymer solubilizate bonds the starting material and provides for increased strength and improved abrasion resistance. This effect, however, is not the result of a double-barreled autogenic bonding and coating process but simply a single-barreled coating process.

The denier of the indivdual synthetic fibers referred to above is preferably in the range of the approximate thickness of the natural fibers mentioned and consequently deniers in the range of from about 1 to about 3 are preferred. However, where greater opacity or increased covering power is desired, deniers of down to about or even about /2 may be employed. Where desired, deniers of up to about 10 or 15 or higher may be used. The minimum and maximum deniers are, of course, dictated by the desires or the requirements for producing a particular bonded fibrous structure.

The weight of the fibrous starting material may be varied within relatively wide limits depending upon the requirements of the finished product. A single thin web of fibers such as produced by a card, may have a weight of from about 30 grains to about 150 grains per square yard. Such a thin fibrous web, however, is so fragile that i ts' handling and manipulation is diflicult. In the usual case, therefore, from about 3 to about l2 or more of these webs are combined and processed in the combined form. In instances where products having a greater weight are desired, starting material weights of as high as about 3000 grains or more per square yard may be processed. Within the more Commercial aspects of the present invention, however, starting material weights of from about 150 grains per square yard-to about 1750 grains per square yard are contemplated.

The fibrous starting material which is processed in accordance with the present invention is preferably prepared by carding techniques. However, other starting fibrous materials such as those produced by air deposition methods, liquid paper making processes, garnetting, combined processes, and the like may be used.

The lengths of the fibers in the starting material will normally vary from about /2 inch in length up to about 2% inches or more in length, depending upon the particular properties and characteristics required or desired in the resulting product. If desired, and particularly where the formation of the fibrous starting material permits, shorter fibers extending from about /2 inch in length down to about ,5 2 of an inch in length may be used. lllust'rativeof such shorter fibers are woodpulp fibers, cotton linters, or any of the previously-mentioned natural or synthetic fibers in lengths less than about /2 inch and down to about 34, of an inch. Such shorter fibers may be included in any desired proportion varying from to 100%, depending upon the method of formation selected for preparing the fibrous starting material.

Other starting materials such as fabrics containing in- I teiengaged orintermatted fibers which are woven, knitted, braided, felted, or the like, may be employed. Similarly improved properties, particularly enhanced abrasion rej'sis tanc'e, are obtained therein as a result of the application of the principles of the present inventive concept to such fabricated materials.

The amount of the fusible polymer which is dissolved in the chloral solution will vary depending upon the amount which is desired to be deposited. Normally, as high a concentration as possible is desired for commercial reasons and from about 2 grams to about 20 grams of the dissolved fusible material in a 100 gram solution (2% to 20% by weight) has been found to be most advantageous. Where other percentages of dissolved synthetic polymeric solids are desired, down to 1 gram or up to 25 or 30 grams in a 100 gram solution may be used.

The amount of dissolved material which is deposited on the fibrous material varies according to the conditions under which the solution is applied and under normal circumstances the amount deposited will range from about 5% to about by Weight, based on the weight of the starting material, calculated as dry add-on by solids. For example, up to' 200% by weight of wet pick-up may be accomplished in one pass of the starting material through a bath of the treating composition. If the concentration of the treating composition is 5 by weight, for example, a single pass may thus deposit up to 10% by weight of the dissolved material. Additional passes may be provided whereby additional amounts of polymeric material be deposited.

The material to be deposited on the fibrous starting was may beso deposited by immersion or dipping proc'esses, by spraying, by roll coating techniques, or'by any desired method. Normal temperatures and pressures may be employed and room temperature and atmospheric pressure are most convenient and preferable. Elevated tem peratures and increased pressures may be employed, where desired or required.

The invention will be further described in greater detail by reference to the accompanying drawing in which the figure is a schematic representation of a typical up to 100% by weight or more may method of utilizing the principles of the present invention.

In the illustrative figure, there is shown an untreated fabric being delivered from the left, as viewed in the figure, from any desired supply means. The fabric is guided over a rotatable roller and is immersed in the treating solubilizate solution containing the dissolved polymeric material. The fabric is then Withdrawn from the treating solution, is passed over a rotatable guide roller and is then passed through the nip of a pair of adjustable pressure rollers whereby the amount of solubilizate pickup can be controlled.

The treated fabric is then advanced over another rotatable guide roller and is led downwardly to be treated, preferably by being immersed in an aqueous coagulating or regenerating bath in which the dissolved polymeric material precipitates out and is deposited on the fabric. The coated fabric passes upwardly and out of the aqueous coagulating bath and is guided over an other rotatable roller and is advanced between the nip of a second pair of adjustable pressure rollers. The coagulating bath need not necessarily be an aqueous solution. Other non-solvents for the material to be deposited may be employed. Acetone, alcohol, benzene, and the like may be used, for example.

The coated fabric is then advanced, in turn, over rotatable guide rollers and into successive neutralizing baths containing, respectively, a basic material, such as a dilute solution of sodium bicarbonate or sodium hydroxide, and through a dilute acidic solution, such as a weak acetic acid. These neutralizing baths are employed to take care of any acidity present. Quite often, traces of hydrochloric acid in amounts of 1% approximately are found in technical grade chloral. Removal of such acidity is particularly desirable when fibers subject to acidic hydrolysis are employed.

The coated and neutralized fabric is then washed in an aqueous bath to remove salts and traces of other materials and is then advanced to a suitable drying means.

The invention will :be further described in greater detail by the following specific examples. It should be understood, however, that although these examples may describe in particular detail some of the more specific features of the invention, they are given primarily for purposes of illustration and the invention in its broader aspects is not to be construed as limited thereto.

Example I A aqueous chloral solution is prepared by mixing 1800 by volume of technical grade chloral liquid (specific gravity 1.5 and containing at least 96% chloral) with 200 parts by volume of water. 200 grams of'chopped Dacron polyethylene terephthalate polyester fibers (1 /2 denier) are added for each 2 liters of aqueous chloral solution and dissolved therein. The pH of the resulting solution is low (about 1) and suflioient sodium carbonate is added to raise the pH to about 5.2. The resulting chloral solution contains approximately 6 /2 grams of dissolved polyester per 100 grams of solution.

-A fn'onwoven fabric Weighing 250 grains per square yard and comprising viscose rayon fibers (1%; inches length and 1 /2 denier) and lightly prebounded with viscose is: (1) passed through the polyester-chloral solubilizate (see the figure); (2) passed through nip rolls under 5 pounds pressure to control the amount of polyester addo'n; '(3) passed through a cold water bath to coagulate the polyester and deposit it on the nonwoven fabric; (4) passed between nip rolls under 10 pounds pressure to remove excess water; (5) passed through a dilute base (5% sodium bicarbonate) and (6) a dilute acid (5% acetic "acid) for neutralization purposes; 7) given a water rinse to remove salts; and (8) air dried.

Representative samples are subjected to abrasion testing in a standard Wyzenbeek machine. The treated sample nonwoven fabric and the untreated control nonwoven fabric are tested against '16 ounce cotton duck to 1000 cycles. Only minor deterioration develops in the treated sample nonwoven fabric Whereas the untreated control nonwoven fabric is substantially destroyed.

Insofar as launderabi lity is concerned, representative samples of treated and untreated nonwoven fabrics are subjected to standard (170 F.) washing cycles in a Bendix automatic washer. The treated samples show slight evidence of pilling, whereas the untreated samples are disintegrated completely.

The polyester treatment thus drastically strengthens and improves the abrasion resistance and laundering durability of the nonwoven fabric. It is to be noted, however, that the bonding of the nonwoven fabric is essentially due to the coating only and that there is essentially no autogenic bonding. The treated fabrics are useful for industrial filtering purposes and as interlining fabrics, when in desirable weights.

Example 11 A 90% aqueous chloral solution is prepared by mixing 1800 parts by volume of technical grade chloral liquid (specific gravity 1.5 and containing at least 96% chloral) with 200 parts by volume of water. 200 grams of chopped Dacron polyethylene terephthalate polyester fibers (1 /2 denier) are added for each 2 liters of aqueous chloral solution and dissolved therein. The pH of the resulting soltuion is low (about 1) and suificient sodium carbonate is added to raise the pH to about 5.2. The resulting chloral solution contains approximately 6 /2 grams of dissolved polyester per 100 grams of solution.

A non-woven fabric weighing 250 grains per square yard and comprising lightly prebonded (polyvinyl alcohol, /2%) polyethylene terephthalate :Dacron fibers (1 /2 inches length and 1 /2 denier) is: (1) passed through the polyester-chloral solubilizate (see the figure); (2) passed through nip rolls under 5 pounds pressure to control the amount of polyester add-on; (3) passed through a cold water bath to coagulate the polyester and deposit it on the nonwoven fabric; (4) passed between nip rolls under pounds pressure to remove excess water; (5) passed through a dilute base (5% sodium bicarbonate) and (6) a dilute acid (5% acetic acid) for neutralization purposes; (7) given a water rinse to remove salts; and (8) air dried.

Representative samples are subjected to abrasion testing in a standard Wyzenbeek machine. The treated sample nonwoven fabric and an untreated control nonwoven fabric are tested against 16 ounce cotton duck to 1000 cycles. Only minor deterioration develops in the treated sample nonwoven fabric whereas the untreated control nonwoven fabric is substantially destroyed. The dry-cleaning properties of the treated fabrics are improved over untreated fabrics; they can be successfully commercially dry cleaned whereas the untreated fabrics will physically fail commercial dry cleaning.

The polyester treatment thus drastically strengthens and improves the abrasion resistance of the nonwoven fabric without any loss in its fibrous character. The bonding of the fibers is excellent and is due to the double-barreled efiect of the coating and the autogenic bonding. The treated fabrics are useful for industrial filtering Example III A aqueous chloral solution is prepared by mixing 1800 parts by volume of technical grade chloral liquid (specific gravity 1.5 and containing at least 96% chloral) with 200 parts by volume of water. 200 grams of chopped Dacron polyethylene terephthalate polyester fibers (1 /2 denier) are added for each 2 liters of aqueous chloral solution and dissolved therein. The pH of the resulting solution is low (about 1) and suificient sodium carbonate is added to raise the pH to about 5.2. The resulting chloral solution contains approximately 6 /2 grams of dissolved polyester per 100 grams of solution.

A lightly prebonded nonwoven fabric weighing 250 grains per square yard and comprising 50% by weight of polyethylene terephthalate Dacron fibers (1 /2 inches length and 1 /2 denier) and 50% by weight of viscose rayon fibers (1%;; inches length and 1 /2 denier) is: (1) passed through the polyester-chloral solubilizate (see the figure); (2) passed through nip rolls under 5 pound-s pressure to control the amount of polyester add-on; (3) passed through a cold water bath to coagulate the polyester and deposit it on the nonwoven fabric; (4) passed between nip rolls under 10 pounds pressure to remove excess water; (5) passed through a dilute base (5% sodium bicarbonate) and (6) a dilute acid (5% acetic acid) for neutralization purposes; (7) given a water rinse to remove salts; and (8) air dried.

Representative samples are subjected to abrasion testing in a standard Wyzenbeek machine. The treated sample nonwoven fabric and an untreated control nonwoven fabric are tested against 16 ounce cotton duck to 1000 cycles. Only minor deterioration develops in the treated sample nonwoven fabric whereas the untreated control nonwoven fabric is substantially destroyed.

The polyester treatment thus drastically strengthens and improves the abrasion resistance of the nonwoven fabric without any loss in its fibrous character. The treated fabrics are useful for industrial filtering purposes and as interlining fabrics, when in desirable weights.

Example IV A 90% aqueous chloral solution is prepared by mixing 1800 parts by volume of technical grade chloral liquid (specific gravity 1.5 and containing at least 96% chloral) with 200 parts by volume of water. 200 grams of chopped nylon 66 polyarnide fibers (1 /2 denier) are added for each 2 liters of aqueous chloral solution and dissolved therein. The pH of the resulting solution is low (about 1) and sufficient sodium hydroxide is added toraise the pH to about 5. The resulting chloral solution contains approinrnately 6 /2 grams of dissolved polyamide per 100 grams of solution.

A nonwoven fabric weighing 250 grains per square yard and comprising polyethylene terephthalate Dacron fibers (1 /2 inches length and 1 /2 denier) and lightly prebonded with polyvinyl alcohol is: (1) passed through the polyarnide-chloral solubilizate (see the figure); (2) passed through nip rolls under 5 pounds pressure to control the amount of polyarnide add-on; (3) passed through a cold water bath to coagulate the polyamide and deposit it on the nonwoven fabric; (4) passed between nip rolls under 10 pounds pressure to remove excess water; (5) passed through a dilute base (5% sodium bicarbonate) and 6) a dilute acid (5% acetic acid) for neutralization purposes; (7) given a water rinse to remove salts; and (8) air dried.

Representative samples are subjected to abrasion testing in a standard Wyzenbeek machine. The treated sample nonwoven fabric and an untreated control nonwoven fabric a-re tested against 16 ounce cotton duck to 1000 cycles. Only minor deterioration develops in the Example V The procedures of Example I are followed substantially as set forth therein with the following exception: the fabrics are woven cotton, Weighing 5.5 ounces per square yard. After the initial exothermic reaction resulting from the mixing of chloral and water subsides and the solution cools to room temperature, some crystallization of chloral hydrate is noted. The addition of by weight of ethylene glycol prevents such crystallization. The physical testing, as regards breaking load, shows improved results comparable to those obtained for nonwoven fabrics. The abrasion tes-tsare against fine emery 'cloth to 75 cycles, with (l) the treated sample having excellent abrasion resistance and showing little wear or abrasion and (2) the untreated control fabric having poorer abrasion resistance and showing considerable wear or abrasion.

Example VI 7 The procedures oil-Example II are followed substan- I tially as set forth therein with the exception that a 90% aqueous chloral solution is prepared by mixing 540 parts by volume of chloral with 60 parts by volume of water at room temperature. In each 25 parts of the chloral solution, there is dissolved 2.824 parts of clean Dacron polyethylene te rephthalate polyester fiber having a staple length of 1%; inches and a denier of 1 /2. The resulting aqueous chloral solution contains approximately 7.3 grams of dissolved polyester per 100 grams of solution.

The remaining procedures of Example II are followed substantially as set forth therein with the results of the testing of the treated samples in this example being comparable to the improved results obtained for the treated samples in Example II. There is no loss in the fibrous character of the fabric.

Example VII The procedures of Example II are followed substantially as set forth therein with the exception that an 80% aqueous chloral solution is prepared by mixing 480 parts by volume of chloral with 120 parts by volume of water at room temperature. In each 25 parts of the chloral solution there is dissolved 2.295'parts of clean Dacron polyethylene terephthalate polyester fiber having a staple length of 1% inches and a denier of 1 /2. The resulting aqueous chloral solution contains approximately 6.1 grams of dissolved polyester per 100 grams of solution.

The remaining procedures of Example H are followed substantially as set forth therein with the results of the testing of the treated samples in this example being comparable to the improved results obtained for the treated samples in Example 11.

Example VIII The procedures of Example II are followed substantially as set forth therein with the exception that a 70% aqueous chloral solution is prepared by mixing 420 parts by volume of chloral with 180 parts by volume of water at room temperature. In each 25 parts of the chloral solution there is dissolved 1.775 parts of clean Dacron polyethylene terephthalate polyester fiber having a staple length of 1% inches and a denier of 1 /2. The resulting aqueous chloral solution contains approximately 4.8 grams of dissolved polyester per 100 grams of solution.

The remaining procedures of Example II are followed substantially as set forth therein with the results of the testing of the treated samples in this example being comparable to the improved results obtained for the treated samples in Example H.

Example IX The procedures of Example II are followed substantially as set forth therein with the exception that a 60% aqueous chloral solution is prepared by mixing 360 parts by volume of chloral with 240 parts by volume of Water at room temperature. In each 25 parts of the chloral solution there is dissolved 0.710 part of clean Dacron polyethylene'terephthalate polyester fiber having a staple length of 1%; inches and a denier of 1 /2. The resulting aqueous chloral solution contains approximately 1.9 grams of dissolved polyester per 100 grams of solution. The remaining procedures of Example II are followed substantially as set forth therein with the results of the testing of the treated samples in this example being comparable to the improved results obtained for the treated samples in Example 11.

Example X The procedures of Example II are followed substantially as set forth therein with the exception that the amount of dissolved polyester is increased so that the aqueous chloral solution contains 13 grams of dissolved polyester per 100 grams of aqueous chloral solution. The increased strength and improved abrasion resistance are comparable to the improved results of Example II. No loss in fibrous character of the fabric is noted.

Although several specific examples of the inventive concept have been described, the same should not be construed as limited thereby nor to the specific features mentioned therein but to include various other equivalent features as set forth in the claims appended hereto. It is understood that any suitable changes, modifications and variations may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A method of improving the physical properties of a fibrous structure containing potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral which comprises: forming a fibrous structure comprising at least about 5% by weight of potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral and less than about by weight of fibers adhesively unafiected by aqueous chloral; treating the fibrous structure with an aqueous chloral solution containing dissolved therein a synthetic, polymeric, high molecular weight material capable of dissolving in aqueous chloral solution; whereby the potentially adhesive fibers are rendered tacky and are bonded to each other at their points of contact; and treating said bonded fibrous structure with an aqueous coagulating media whereby the dissolved synthetic, polymeric, high molecular weight material is precipitated out of the chloral solution and is deposited on the potentially adhesive fibers whereby they are coated in addition to being bonded, thus providing properties of increased strength and improved abrasion resistance in the fibrous structure without loss of its fibrous character.

2. A method of improving the physical properties of a fibrous structure containing potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral which comprises: forming a fibrous structure comprising at least about 5% by weight of potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral and less than about 95% by Weight of fibers adhesively unaffected by aqueous chloral; treating the fibrous structure with an aqueous chloral solution containing dissolved therein a synthetic, poly meric, high molecular Weight material capable of dis solving in aqueous chloral solution, whereby the potentially adhesive fibers are rendered tacky and are bonded to each other at their points of contact; treating said bonded fibrous structure with an aqueous coagulating media whereby the dissolved synthetic, polymeric, high molecular weight material is precipitated out of the chloral solution and is depositedon the potentially adhesive fibers whereby they are coated in addition to being bonded; and drying the bonded and coated fibrous structure thus providing properties of increased strength and improved abrasion resistance in the fibrous structure without loss of its fibrous character.

3. A method of improving the physical properties of a fibrous structure containing potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral which comprises: forming a fibrous structure comprising at least about by weight of potentially adhesive fibers capable of being rendered tacky by treat ment with aqueous chloral and less than about 95% by weight of fibers adhesively unaffected by aqueous chloral; treating the fibrous structure with an aqueous chloral solution containing from about 45% to about 99% by volume of chloral, said aqueous chloral solution containing dissolved therein from about 1 gram to about 30 grams of a synthetic, polymeric, high molecular Weight material capable of dissolving in aqueous chloral per 100 grams of aqueous chloral solution, whereby the potentially adhesive fibers are rendered tacky and are bonded to each other at their points of contact; and treating said bonded fibrous structure with an aqueous coagulating media whereby the dissolved synthetic, polymeric, high molecular weight material is precipitated out of the chloral solution and is deposited on the potentially adhesive fibers whereby they are coated in addition to being bonded, thus providing properties of increased strength and improved abrasion resistance in the fibrous structure without loss of its fibrous character.

4. A method of improving the physical properties of a fibrous structure containing potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral which comprises: forming a fibrous structure comprising at least about 5% by weight of potentially adhesive fibers capable of being rendered tacky by treatment with aqueous chloral and less than about 95% by weight of fibers adhesively unaffected by aqueous chloral; treating the fibrous structure with an aqueous chloral solution containing from about to about by volume of chloral, said aqueous chloral solution containing dissolved therein from about 1 gram to about 20 grams of a synthetic, polymeric, high molecular weight material capable of dissolving in aqueous chloral per grains of aqueous chloral solution, whereby the potentially adhesive fibers are rendered tacky and are bonded to each other at their points of contact; and treating said bonded fibrous structure with an aqueous coagulating media whereby the dissolved synthetic, polymeric, high molecular weight material is precipitated out of the chloral solution and is deposited on the potential- 1y adhesive fibers whereby they are coated in addition to being bonded, thus providing properties of increased strength and improved abrasion resistance in the fibrous structure without loss of its fibrous character.

5. A method as defined in claim 1 wherein the potentially adhesive fibers and the synthetic, polymeric, high molecular weight material deposited thereon have the same organic chemical nature.

6. A method as defined in claim 1 wherein the potentially adhesive fibers and the synthetic, polymeric, high molecular weight material deposited therein are polyethylene terephthalate polyesters.

7. A fibrous structure resulting from the method of claim 1.

Rodman Nov. 15, 1955 De Witt June 26, 1956 

1. A METHOD OF IMPROVING THE PHYSICAL PROPERTIES OF A FIBROUS STRUCTURE CONTAINING POTENTIALLY ABHESIVE FIBERS CAPABLE OF BEING RENDERED TACKY BY TREATMENT WITH AQUEOUS CHLORAL WHICH COMPRISES: FORMING A FIBROUS STRUCTURE COMPRISING AT LEAST ABOUT 5% BY WEITH OF POTENTIALLY ADHESIVE FIBERS CAPABLE OF BEING RENDERED LACKY BY TREATMENT WITH AQUEOUS CHLORAL AND LESS THAN ABOUT 95% BY WEIGHT OF FIBERS ADHESIVELY UNAFFECTED BY AQUEOUS CHLORAL; TREATING THE FIBROUS STRUCTURE WITH AN AQUEOUS CHLORAL SOLUTION CONTAINING DISSOLVED THEREIN A SYNTHERIC, POLYMERIC, HIGH MOLECULAR WEIGHT MATERIAL CAPABLE OF DISSOLVING IN AQUEOUS CHLORAL SOLUTION, WHEREBY THE POTENTIALLY ADHERSIVE FIBERS ARE RENDERED TACKY AND ARE BONDED TO EACH OTHER AT THEIR POINTS OF CONTACT; AND TREATING SAID BONDED FIBROUS STRUCTURE WITH AN AQUEOUS COAGULATING MEDIA WHEREBY THE DISSOLVED SYNTHETIC, POLYMERIC, HIGH MOLECULAR WEIGHT MATERIAL IS PRECIPHATED OUT OF THE CHLORAL SOLUTION ANDIS DEPOSITED ON THE POTENTIALLY ADHESIVE FIBERS WHEREBY THEY ARE COATED IN ADDITION TO BEING BONDED, THUS PROVIDING PROPERTIES OF INCREASED STRENGTH AND IMPROVED ABRASION RESISTANCE IN THE FIBROUS STRUCTURE WITHOUT LOSS OF ITS FIBROUS CHARACTER. 